Single thread chain stitch forming means for use in a conventional sewing machine

ABSTRACT

THIS INVENTION RELATES TO SINGLE THREAD CHAIN STITCH FORMING MEANS FOR USE WITH A SEWING MACHINE PROVIDED WITH A SHUTTLE MECHANISM ADAPTED IN REPETITIVE OPERATION FOR FORMING NORMAL STITCHES BY INTERTWINING UPPER AND LOWER THREADS WHICH SINGLE THREAD CHAIN STITCH FORMING MEANS PERMIT THE FORMATION OF SINGLE THREAD CHAIN STITCHES WITH THE UPPER THREAD ALONG WHEN THE THREAD CHAIN FORMING MEANS IS MOUNTED ON THE SHUTTLE HOOK IN PLACE OF A CONVENTIONAL BOBBIN AND BOBBIN CASE.

N 1971 HIDEKI KUWAJIMA 3,

SINGLE '1' "AD CHAIN STITCH FORMING "BANS FOR USE A CONVENTIONAL SEWING MACHINE Filed Oct. 20. 1969 2 Sheets-Sheet 1 INVENTOR mom Kuun J! M A BY WM awab W ATTORNEY N v- 16. 7 HiD EKI KUWAJIMA 3,620,179

SINGLE THREAD CHA N STITCH PO NG "EARS FOR USE IN A CONVENTIONAL SEWI MACHINE Filed Oct. 20, 1969 2 Sheets-Sheet I Fig.6la) Fig.6) Fig.6/c/ 4 F 'aa) z HmEm Kuununn YMMMW ATTORNEY 5 United States Patent SINGLE THREAD CHAIN STITCH FORMING MEANS FOR USE IN A CONVENTIONAL SEWING MACHINE Hideki Kuwajima, Tokyo, Japan, assignor to Riccar Sewing Machine Co., Ltd., Tokyo, Japan Filed Oct. 20, 1969, Ser. No. 867,578 Int. Cl. Db 1/14 US. Cl. 112-168 1 Claim ABSTRACT OF THE DISCLOSURE This invention relates to single thread chain stitch forming means for use with a sewing machine provided with a shuttle mechanism adapted in repetitive operation for forming normal stitches by intertwining upper and lower threads which single thread chain stitch forming means permit the formation of single thread chain stitches with the upper thread alone when the thread chain forming means is mounted on the shuttle hook in place of a conventional bobbin and bobbin case.

BACKGROUND OF THE INVENTION Various proposals have hitherto been made for forming single thread chain stitches by using sewing machines adapted for forming normal stitches. The methods proposed include, for example, removing the shuttle hook for forming normal stitches from the sliding groove formed in the periphery of the shuttle hook support and substituting therefor a shuttle hook adapted for forming chain stitches, and removing the shuttle mechanism as a whole and mounting a stitch forming device on the shuttle driving shaft. The methods proposed have a disadvantage in that a time-consuming operation is involved in replacing a component part for forming normal stitches with an attachment for forming chain stitches. Full popularization and spread of the use of chain stitch forming means in households has hitherto been hampered by inability to very quickly effect replacements of the component part with the attachment.

SUMMARY OF THE INVENTION The object of the present invention is to provide chain stitch forming means which can readily be mounted on and removed from a sewing machine for forming normal stitches. The chain stitch forming means according to this invention can be mounted on and removed from the shuttle hook pin of the sewing machine for forming normal stitches in the same manner as the lower thread bobbin and lower thread bobbin case are mounted on and removed from the shuttle hook pin when the operator desires to supplement the lower thread. The single thread chain stitch forming means according to this invention can readily be mounted on and removed from a sewing ma chine for forming normal stitches. Moreover, the single thread chain stitch forming means according to this invention is small in size, simple in construction and low in cost as an attachment. The use of the single thread chain stitch forming means according to this invention markedly increases the utility value of sewing machines for forming normal stitches.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects as well as features and advantages of the invention will become evident from consideration of the description set forth hereinafter when considered in conjunction with the accompanying drawings, in which:

FIG. 1 is an exploded perspective view of a conventional shuttle mechanism, with a bobbin and bobbin case being removed from a shuttle hook pin;

FIG. 2 is a perspective view of single thread chain stitch forming means embodying this invention;

FIG. 3 is a front view of a shuttle hook of a conventional shuttle mechanism for a normal stitch forming sewing machine as it is provided with the single thread chain stitch forming means according to this invention;

FIG. 4 is a side view of FIG. 3;

FIG. 5 is a sectional view taken along the line A-A of FIG. 4;

FIGS. 6(a) to 6(a) are front views of the shuttle hook in explanation of the manner in which the single stitch forming means is mounted thereon and removed therefrom;

FIGS. 7(a) to 7(f) are front views of the shuttle hook in explanation of the manner in which single thread chain stitches are formed and FIG. 7(g) is a side view of FIG. 7(e); and

FIG. 8 is a perspective view of a part which may be used for modifying the single thread chain stitch forming means shonw in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of this invention will now be explained with reference to the drawings. In FIGS. 1, 3, 4 and 5, 1 designates a shuttle hook support and 2 a shuttle book which is rotatably received in a groove formed in the periphery of said shuttle hook support 1. 3 is a shuttle hook pin, 4 a pointed end of the shuttle hook (see FIGS. 3 to 5), 5 a base of the pointed end of the shuttle hook, 6 a first projection extending from the base of the pointed end of the shuttle book, 7 a second projection extending from an inner portion 8 of the shuttle hook 2 in parallel relation with the first projection 6, 9 a bobbin, and 10 a bobbin case, said bobbin 9 being fitted in said bobbin case 10 and mounted on the shuttle hook pin 3. The aforementioned construction is similar to known shuttle mechanisms.

The single thread chain stitch forming means according to this invention is generally designated 11 in FIG. 2. The stitch forming means 11 comprises a cylinder 13 formed with a 'bore 12 for receiving the shuttle hook pin 3 therein, a blade member 14 having a thickness smaller than that of the outer wall of the cylinder 13, and an arm 15 projecting outwardly from the cylinder 13 substantially at right angles. An offset portion 16 is formed at the free end of said arm 15.

Formed on one side of the cylinder 13 is a head 18 which is substantially elliptic in its peripheral plan and formed with a triangular protrusion 17 in one direction as seen from the side. Said head 18 is connected to the cylinder 13 by a straight rod 19 extending from the cylinder 13 to the inner surface of the head 18 and a curved rod 20 contiguous with the elliptic periphery of the head 18 and bent substantially at right angles. The aforementioned portions are formed integral with one another as by a synthetic resinous material to provide a unit of the single thread chain stitch forming means.

The shape of the blade member 14 and arm 15 as shown is best suited for taking advantage of the resilience of a synthetic resinous material from which the unit is formed. The protrusion 17 performs the functions of facilitating the mounting and removal of the single lock stitch forming means by fingers and also preventing the breaking of thread as subsequently to be described.

As seen in FIGS. 3 to 5, the unit of single thread chain stitch forming means according to this invention is constructed in such a manner that when the unit is mouted in the shuttle hook 2 after the bobbin 9 and bobbin case 10 are removed therefrom, the unit 11 is secured in place in the shuttle hook with the bore 12 of the cylinder 13 being fitted over the shuttle hook pin 3 and the offset portion 16 at the free end of the arm 15 engaging with the first projection 6 extending from the base of the pointed end of the shuttle hook 2. The stitch forming means 11 can be mounted in the shuttle book 2 and brought to the aforementioned position by the process presently to be described. As shown in FIG. 6(a), the bore 12 of the cylinder 13 is first fitted over the shuttle hook pin 3 in such a manner that the blade member 14 and arm extending outwardly from the outer periphery of the cylinder 13 do not strike the inner portion 8 of the shutle book 2 and then the unit is rotated in the clockwise direction as shown by the arrow. This causes the arm 15 to be bent slightly and brought into engagement with the underside of the first projection 6 extending from the base 5 of the pointed end 4, with the blade member 14 abutting against an ottset portion 2 on the inner side of the shuttle hook 2 as shown in FIG. 6(b). The offset portion 2 on the inner side of the shuttle hook 2 is not formed especially for mounting the stitch forming means 11 according to this invention but forms a standardized portion of the shuttle hook formed in the conventional process of machining on shuttle hooks.

Further rotation of the unit 11 in the clockwise direction from the position shown in FIG. 6(b) causes the blade member 14 which abuts against the offset portion 2' on the inner side of the shuttle hook 2 to be bent by its resilience, with the offset portion 16 at the free end of the arm 15 being snapped into engagement with the forward end of the first projection 6 as seen in FIG. 5. When the unit 11 is in this position, the resilient restoring force of the blade member 1-4 tending to rotate the unit in the anticlockwise direction keeps the offset portion 16 at the free end of the arm 15 in firm engagement with the forward end of the first projection 6. In addition, when maintained in abutment against the offset portion 2' on the inner side of the shuttle hook, the blade member 14 is maintained on one side thereof in contact with the inner wall of the shuttle book, so that the axial movement of the unit 11 along the shuttle hook pin 3 can be prevented.

The unit of single thread chain stitch forming means 11 mounted in the shuttle hook 2 by the aforementioned process permits to form single thread chain stitches by using upper thread alone by means of a normal stitch forming sewing machine. The unit 11 can be removed from the shuttle hook 2 by the following process when desired: The single thread chain stitch forming means 11 is rotated in the clockwise direction from a position in which the shuttle hook 2 is disposed after it has stopped. This causes the portion 16 at the free end of the arm 15 to be released from engagement with the forward end of the first projection 6 extending from the base 5 of the pointed end of the shuttle book 2. At the same time, the blade member 14 is further bent by its resilience as it is released from engagement with the offset portion 2 and moved along the inner side of the shuttle hook 2 toward the forward end of the first projection 6 till it is restored to its original shape when it is released from engagement with the forward end of the first projection 6. When the unit 11 is in this position, it can readily be removed from the shuttle hook 2 by reversing the process of mounting the unit in the shuttle hook as described with reference to FIG. 1. It will thus be appreciated that the stitch forming means 11 according to this invention can readily be mounted in and removed from the shuttle hook by rotating the former in the clockwise direction on the shuttle hook pin of the latter.

From the foregoing description, it will be evident that when the single thread chain stitch forming means 11 constructed as aforementioned is mounted in the shuttle book 2, it is possible to form usual single thread chain stitches by using upper thread alone of the sewing machine.

Forming of a single thread chain stitch will now be explained with reference to FIGS. 7(a) to 7 (3).

FIG. 7(a) shows a needle 21 in a lowered position, and a loop of thread 22 caught by the pointed end 4 of the shuttle hook 2 as the latter is rotated in the clockwise direction.

In FIG. 7 (b), the loop of thread 22 caught by the pointed end 4 of the shuttle hook 2 is shown as having been drawn around by the rotating shuttle hook, with the portion of the loop of thread 22 shown in a dotted line being released from engagement with the base 5 of shuttle hook and pulled upwardly by a known lever mechanism immediately before the shuttle hook 2 reverses its direction of rotation after having made a one-half revolution in the clockwise direction. This is clearly understood from the principles on which the operation of conventional normal stitch forming sewing machines are based. The loop of thread released from the base 5 in this way finds its way into the rear of the head 18 of the unit 11 where the loop is caught by the straight rod 19 connecting the head 18 and cylinder 13 and an inner side a of the curved rod 20 and prevented from being pulled upwardly by the lever mechanism.

In FIG. 7(a), the shuttle book 2 has further rotated from its position shown in FIG. 7(b) in the anticlockwise direction and the loop of thread 22 is pushed upwardly and forwardly by an end edge 8' of the inner portion 8 of the shuttle hook 2 and moved to the lower rear portion of the head 18 along the curved rod 20.

FIG. 7(d) shows the shuttle hook 2 as it has completed its rotation in the anticlockwise direction and about to begin its rotation in the clockwise direction again. The left side of the thread of loop 22 has been transferred to the front of the head 18 along an outer side b of the curved rod 20 and the pointed end 4 has caught a second loop of thread 22 within said loop of thread 22 to repeat the same operation as aforementioned.

In FIG. 7(e), the shuttle hook 2 is shown as having rotated through about degrees from its position shown in FIG. 7(d) in the clockwise direction. As the shuttle hook 2 moves from the position shown in FIG. 7 (d) to the position shown in FIG. 7(e), the loop of thread 22 is moved entirely to the front of the head 18 and pulled upwardly to be released from engagement with the end portion of the triangle-shaped protrusion 17 while being displaced forwardly thereby (see FIG. 7(g)). The pulling of the loop of thread 22 upwardly along the protrusion 17 in releasing the loop of thread 22 from engagement with the protrusion 17 is conducive for preventing the twisting of the loop of thread. The arrangement is also eifective in imparting a suitable tension to the thread so as to prevent the loosened loop of thread from entering the groove on the peripheral surface of the shuttle hook 2 and being broken as the shuttle hook reverses its direction of rotation from the clockwise to the anticlockwise direction.

FIG. 7(f) shows the shuttle hook 2 about to begin its rotation in the anticlockwise direction after completing its rotation in the clockwise direction. It will be seen that the second loop of thread 22 is released from engagement with the base 5 of the pointed end 2 and caught by the straight rod 19 and curved rod 20 as shown in FIG. 7(b), with the first loop of thread 22 being reduced in size and fastening the base of the second loop of thread 22', thereby forming a single thread chain stitch.

It will be evident that if the cycle of operation described hereinabove is repeated while the shuttle hook ro tates in both directions alternately, it is possible to form a series of single thread chain stitches.

The blade member 14 formed integrally with and projecting outwardly from the outer periphery of the cylinder 13 of the single thread chain stich forming means 11 according to this invention may be replaced by a member shown in FIG. 8. Said member may be formed of a resilient material independently of the unit 11 and comprise a fitting portion 23 bent into a shape conforming to the shape of cylinder 13, and an extending blade-like portion 24. The member constructed as aforementioned can be fitted over the cylinder 13 and secured in place so that it may function as the blade member of the single thread chain stitch forming means of this invention.

From the foregoing description, it will be appreciated that the present invention ofiers the advantage of increasing the utility value of a normal stitch forming sewing machine, because the single thread chain stitch forming means provided by this invention permits to readily form single thread chain stitches if a unit of said means is mounted on the shuttle hook pin of the shuttle hook of ordinary normal stitch forming sewing machine after the bobbin and bobbin case are removed therefrom.

What is claimed is:

l. Stitch forming means arranged to be mounted on the shuttle hook pin of the shuttle lock of an ordinary sewing machine capable of forming normal stitches for forming single chain stitches by using the upper thread alone, said stitch forming means comprising a cylinder arranged to be fitted over the shuttle hook pin, a blade member projecting outwardly from the outer periphery of said cylinder, an arm extending outwardly from the outer periphery of said cylinder and bent substantially at right angles, said blade member and said arm being disposed in side by side relationship, and a head substantially elliptic in its peripheral plan and being disposed on one side of said cylinder, said head being formed with a triangular protrusion in one direction as seen from the side, a straight rod connected at one end to said cylinder and at the other end to said head, a curved rod secured at one end to said cylinder and at its other end to said head, and the aforementioned elements being formed integrally as a unit.

References Cited UNITED STATES PATENTS 472,512 4/1892 Russell 112168 2,999,472 9/1961 Yamano l12-l68 3,006,298 10/1961 Johnson 112232 X 3,028,823 4/1962 O-ocho 112168 X 3,253,560 5/1966 Ketterer et a1. 112-168 3,447,498 6/1969 Eguchi 112l68 UX ALFRED R. GUEST, Primary Examiner 

